Device for pressing insulating material around the long and straight-lined coil members of motors and generators



H. SCHUMANN FOR PRESSING INSULATI LONG 2,824,338 NG MATERIAL AROUND MEMBERS Feb. 25, 1958 DEVICE THE Filed Jan. 7, 1.954

AND STRAIGHT-LINED C 05 MOTORS AND GENERAT I 3 Sheets-Sheet 1 Feb. 25, 1958 DEV FOR, PRESSING INSULAT LONG-AND STRAI, 4.:

OF uoToRs Filed Jan. 7, 1954 H. SCHUMANN 2,824,338

MATERIAL AROUND C L MEMBERS GENERAT 3 Shuts-Sheet 2 v INVENTOP I HeMTJLh $61 Yvsqvm EA; wr ys Feb. 25, 1958 H. SCHUMANN 2,824,338

DEVICE FOR passsmc INSULATING MATERIAL AROUND THE LONG AND STRAIGHT-LINED COIL MEMBERS OF uo'roRs AND summons Filed Jan. 7, 1954 :s' Sheets-Sheet a INVENTOP Hefinneh Sahib u n v *9 Tws United States Patent C) DEVICE FOR PRESSING INSULATING MATERIAL AROUND THE LONG AND STRAIGHT-LINED Cgg MEMBERS OF MOTORS AND GENERA- T Heinrich Schiimann, Lubeck, Germany Application January 7, 1954, Serial No. 402,761 8 Claims. (Cl. 18-16) The present invention relates to a device for pressing the insulating means around the long and straight-lined coil portions of motoror generator coils.

Devices for pressing the insulating means with correct cross-section around coil portions of this kind, are already known to the art. These known pressing devices consist of a plurality of pressure units provided each with an elongated lateral pressure plate and an elongated upper pressure plate by means of which the coil portions, surrounded by the insulating material and arranged in an elongated continuous angular steel member, are pressed against the flanges of said angular steel member. The plurality of pressure units may be shiftably mounted beside one another on a bed-plate in longitudinal direction of the latter and provided with means for locking them in their position on the bed-plate at suitable distances from each other, whereby the distance between the plurality of pressure units is bridged in longitudinal direction of the bed-plate by the aforesaid continuous angular steel member in which the coil portion is arranged. Pressure units of this known type have so far been designed as screw presses consisting of a frame work provided with one or a plurailty of screws adapted to exert pressure in horizontal direction against the aforesaid lateral pressure plate, and of one or a plurality of screws adapted to exert pressure in vertical direction against the aforesaid upper pressure plate. Instead of using screw pressure, it is also possible to employ eccentric presses by means of which, with the aid of manually operated eccentrics, double-armed levers are rotated which have one of their lever arms act upon the lateral pressure plate or upon the upper pressure plate, so that thereby an all-round pressure is exerted upon the coil portion. But all known devices of this kind require a separate actuation of the screws or eccentrics which act upon the lateral pressure plate and upon the upper pressure plate, so that for the actuation of the pressure units several workmen are always needed in order to obtain, a uniform compression in horizontal as well as vertical direction.

The object of the invention, therefore, is to device the pressure units in such a way that a considerably simplified operation of the pressure units is thereby enabled.

According to the application, the invention resides essentially in the feature that. there are supported in the supporting block of the pressure unit two double-armed levers which, by means of a cylinder and a piston hydraulically actuated within the cylinder, have one of their lever arms act upon the upper pressure plate and one act upon the lateral pressure plate, while the second lever arm of one of the levers is coupled to the cylinder, and the second lever arm of the other lever is acted upon by the piston rod.

In a preferred embodiment of this kind, the construction is so devised that the hydraulic cylinder is rigidly connected to one lever arm of an angle lever which is stationarily supported in the supporting block of the pres: sure unit and whose other lever arm rotates the double- 2,824,338 Patented Feb. 25, 1958 "ice armed lever which exerts pressure in vertical direction upon the upper pressure plate, while the free end of the piston rod rotates the second double-armed lever which exerts pressure in horizontal direction against the lateral pressure plate.

7 As in a construction like this, the lever arm which exerts the pressure upon the upper pressure plate can move in upward and downward direction only on the arc of a circle, the upper pressure plate must be so dimensioned that its height at least corresponds to the height of the cross-section of the coil portion, in order to make it possible for the workmen to withdraw, after removal of the upper pressure plate, the coil portion in upward direction from its position between the lateral pressure plate and the vertical flange of the angular steel member. This means that an increase in height of the cross-section of the coil portion likewise necessitates an increase in height of the upper pressure plate, so that for its removal from its position several workmen may be needed.

In order to avoid the use of two heavy upper pressure plates of this kind, the invention proposes to devise the construction in such a way that the double-armed lever which exerts pressure upon the upper pressure plate is rotatably mounted in a pair of supporting arms which are rotatably supported, that is to say, for rotation through a certain predetermined angle, in the supporting block of the pressure unit. Whereby the supporting arms are simultaneously coupled to the angle lever which is rigidly connected to the working cylinder in such a man-v ner that rotation of the angle lever, owing to the shifting of the hydraulic piston primarily, merely causes a rotation of the supporting arms through an angle limited by a stop, while continued rotation of the angle lever results in rotation of only the double-armed lever (whose one arm acts upon the upper pressure plate) about its pivot in the pair of supporting arms. An arrangement like this makes it possible to swing the double-armed lever, whose one arm acts upon the upper pressure plate, out of the area above the coil portion, so that the coil portion as well as the upper pressure plate can without difliculty be arranged from above in pressing position and removed in upward direction from said pressing position. The upper pressure plate employed in a construction of this type may, naturally, be comparatively thin, so that it can easily and conveniently be lifted from the upper surface of the coil portion.

Additional features and advantages of the invention will be understood from a consideration of the following detailed description taken in connection with the accompanying drawings, forming a part of this specification, and in which an embodiment of the invention has been shown by Way of illustration. However, I wish to say that the invention is not confined to any strict conformity with the showing of the drawings, but may be changed or modified, so long as such changes or modifications mark no material departure from the salient features of the invention as expressed in the appended claims.

In the drawings, in which like parts are referred to by the same reference numerals,

Fig, l is a perspective view of a pressure unit;

Fig. 2 is a vertical, cross-section of the pressure unit, showing the several double-armed levers in pressing position;

Fig. 3 is a vertical cross-section of the pressure unit, showing the several double-armed levers in position of rest;

Fig. 4 is a partial vertical cross-section, on an enlarged scale, of a modified form of construction, with the levers inposition of rest;

Fig. 5 is a diagrammatic illustration of the pressure components at various angular positions of the semi-cylindrical, member illustrated. in Fig. 4.

In the embodiment illustrated in the drawings, the pressing device for pressing insulating material around the long and straight-lined coil portions of motorand generator coils, consists of a block 1 shiftably mounted on a bed-plate 2 for shifting, adjustment and locking in longitudinal direction of the bed-plate. The block 1 has an upper horizontally extending supporting surface In which is laterally provided with a vertically extending abutment or stop surface 16, for the arrangement thereon of an elongated cast angular member 3. One of the flanges of the angular member 3 extends in horizontal direction, while the other one of the flanges extends in vertical direction. Arranged in the angular member 3, and indicated in the drawings by the reference character A, is one of the two long and straight lined coil portions, with the insulating material to be pressed around it loosely surrounding its wires, which coil portions are usually known to the art as coil-limbs or coil-members, and arranged in known manner parallel to each other in grooves of the rotor or stator of motors or generators. The block 1 is longitudinally pierced (that is to say, in transverse direction to the longitudinal direction of the bed-plate 2) by a bore-hole, in which slidingly engages a push-rod 4. The push-rod 4 rests with one of its ends against the arm 5a of a double-armed lever whose other arm 5b is brought to bear against a laterally positioned elongated steel plate 6. The steel plate or pressure plate 6 is placed upon the horizontally extending flange 3a of the angular member 3, laterally of the coil portion A. The double-armed lever 51:, 5b is rotatably mounted on the pivot 7, and is caused to bear against one end of the push-rod 4 through pressure exerted against its arm 5a by the spring 8.

Arranged in the block 1, on the other side of the angular member 3, for rotation about the pivot 9, is an angle lever 10 which has one of its arms rigidly connected to the cylinder 11. Positioned in the cylinder 11 is a hydraulically actuated piston provided with a piston-rod 11a whose free end rests against the free end of the pushrod 4. The angle lever 10 rests with a pressure surface 10a against the arm 12a of a double-armed lever 12.

If the construction is so devised that the pivot 13 of the double-armed lever 12 is stationarily arranged in the block 1, the ends of the lever arms 12a and 1212 are caused to swing on arcs of circles having their center in the axis of the pivot 13 whenever rotation of the angle lever 10 is effected by the pressure liquid entering the cylinder 11.

It is, however, advisable to construct the pressing device in such a way that the pivot 13 of the double-armed lever 12 is supported in a pair of supporting arms 14 which are laterally arranged at the block 1 for rotation about a pivot 15. The two supporting arms 14 are elastically coupled to the angle lever 10, which for that pur pose is provided with a flange 10b, to which is pivotally fastened a rod 16 carrying a pressure spring 18, while the supporting arms 14 are provided with a ring-shaped pro ecting portion 17 through which shiftably extends the free end of the rod 16.

The hydraulic pressing device, as disclosed in the present Invention, operates as follows:

When the device is not working, that is to say, when no liquid pressure is exerted upon the piston in the cylinder 11, the double-armed lever 12 is in the position illustrated in Fig. 3, in which the rotatable part 12c of that lever is located somewhat above the upper end of the vertically extending flange 3b of the angle 3. The first thing to do now, is to arrange the elongated pressure plate 6 in its position on the horizontally extending flange 3a of the angle 3. Whereupon the long and straight-lined coil portion A surrounded by the insulating material, is introduced from above into the gap between the flange 3b and the elongated pressure plate 6. Then, the upper elongated steel pressure plate 19 is placed upon the upper surface of the coil portion A, whereby the cross-section of the pressure plate 19 may be a comparatively thin one. After this the cylinder 11 is placed under liquid pressure, so

that the push-rod 4 is forced by the piston-rod 11a against the arm 5a of the laterally positioned double-armed lever 5 which with its upper arm 5b bears against the elongated pressure plate 6. The outward movement of the pistonrod 11a simultaneously causes rotation of the angle lever 10 (because of the rigid connection between the cylinder 11 and the lever 10) about its axis 9, whereby it displaces by means of the spring contrivance 16, 17, 18 the supporting arms 14, and, consequently also the double-armed lever 12, in forward direction into the position illustrated in Fig. 2. From an inspection of the drawings it will be seen that in this latter position the supporting arms 14 rest against the back of the flange 312, so that further displacement of the supporting arms 14 in forward direction is thereby prevented. But the rotation of the angle lever 10 continues, causing compression of the spring 18 and rotation of the double-armed lever 12, whereby the undersurface of the rotatable part 120 of the lever 12 is brought to bear against the elongated pressure plate 19 and thus causes the pressure plate 19 to exert pressure upon the upper side of the coil portion A. At the same time a corresponding lateral pressure is exerted upon the coil portion A by the pressure plate 6 and the double-armed lever 5 whose lever arms 5a and 5b are accordingly dimensioned.

During this pressing action, the coil portion and its insulating material are heated with the aid of heating means provided within the angular member 3, so that the insulating material, consisting for instance of artificial material moldable by heat, is softened by the heat and in that softened condition easily pressed between the wires of the coil portion. For this purpose the angular member 3 may be hollow in its interior and adapted for heating by steam or provided with heating coils for its electric heating.

After the insulating material has thus been pressed around the coil portion A with correct cross-section, the pressure in the cylinder 11 is discontinued, whereupon the movement of the plurality of levers takes place in reversed order.

Depending upon the length of the coil. portions to be worked, a plurality of pressure units of the type described may be arranged on the bed-plate 2 at predetermined distances from each other, which distances, however, are bridged by a common elongated angular member 3. The length of the pressure plates 6 and 19 corresponds to the length of the straight-lined coil portions A.

The ratio of pressure applied to the lateral pressure plate 6 and the upper pressure plate 19 is determined by the length of the lever arms of the double-armed levers 5 and 12 and by the effective length of the arms of the angle lever 10 and can thus be adapted to the working of straight-lined coil portions of a certain predetermined cross-section. If the cross-section of the coil portions to be worked differs in the ratio of height and width from the aforesaid certain cross-section, the ratio of pressure exerted upon the pressure plates 6 and 19 must in the embodiments of 'Figs. 1 to 3, naturally, remain the same, and this may then cause the drawback that the coil portion is compressed, for instance in vertical direction, either too little or too much.

In order to prevent undesired deformations of this 'kind of the cross-sections of the coil portions, and in order to be able to adapt the ratio of pressure in vertical and horizontal direction to varying heights and widths of the coil portion, the invention provides the angle lever 10, which is rigidly connected to the hydraulic cylinder 11, at the place where it bears against the arm 12a of the double-armed lever 12, with an adjustable surface portion 21 in such a way that the surface 21a of the adjustable surface portion 21 can be adjusted at any suitable angle with respect to the bearing surface of the angle lever 10. By means of this angularly adjustable surface portion 21 the resultant of the pressure, exerted by the angle lever 10 via the lever arms 12a and 12b upon the upper pressure plate 19, is resolved into two components, of which one is effective ina direction vertical to'the surface of the adjustable surface portion 2 1 and thus forms the pressure component for the rotation of the'double-armed lever 12, While the-other'pressure-component is absorbed by the bearingof the lever 12.

From an inspection of Fig. 4 of the drawings it will be seen that the angle lever is "provided in its upper surface -10a,'parallel to its axis of rotation 9, with a semicy'lindrical recess 20, in which is arranged a rigid and solid semi-cylindrical member 21 which is provided with a fiat upper surface 21a and rotatable within the recess about its axis 22, so that the flat upper surface 21a can be rotated from its broken line position into an angular full line position, as shown in Fig. 4. In order to make it possible to adjust and lock the flat surface 2 1a o'f the semi-cylindrical member 21 at any desired angle with respect to the upper surface 10a of the angle lever 10, the semi-cylindrical member 21 is provided with a lateral pair of arms 21b which laterally embrace in fork-like fashion the angle lever 10. The forked arms 21b are-provided parallel to the axis 22 with a bore 23 adapted for cooperation with a plurality of bores 24 'provided in the lever 10 and positioned on the same are of -a 'circle around the axis 22 as the bore 23, so that through the bores 23, 24 a bolt can be pushed to thereby lock the 'semi-cylindrical member 21 in any desired angular position of its surface 21a. The arm 12a of the double-armed lever 12 carries at its free end, confronting the semi-cylindrical *member 21, a roll 25, against the circumference of which the flat surface 21a of the semi-cylindrical member 21 is brought to bear. Instead of providing the lever arm 12a with the roll 25, it is also possible to provide it with a rigid cylindrical surface.

The modified construction, as heretofore described and illustrated 'in Figs. 4, and 5 of the drawings, operates as follows:

I "When the semi-cylindrical member 21 is in zero position, as indicated in broken lines, it is retained in said position by its projecting portion 26 engaging in a corresponding recess in the upper surface 19a of the angle lever 10. If the angle lever 10 is actuated by the hydraulic means 11, 11a with the member 21 in the aforesaid zero position, the roll of the lever arm 12a will come to rest against the flat surface 21a of the semicylindrical member 21 at a, so that the entire resulting force P, which is effective vertically of the surface 10a of the angle lever 10, is caused to act upon the lever arm 12a of the double-armed lever 12. If the semi-cylindrical member21 is rotated within the semi-cylindrical recess 20 through a desired angle, the flat surface 21a of the semi-cylindrical member will move into an angular position with respect to the surface 10a of the angle lever 10. The point of contact of the lever arm 12a with the fiat surface 21a will then move from a to b, whereby the length of the lever arm 12a as well as the length'of the effective lever arm of the angle lever 10 will both increase, so that a change in the ratio of pressure will not occur. However, the angular position of the flat surface 21:: produces the result that no longer thelresulting force P acts upon the lever arm 12a, but only the power component C which is effective in vertical direction of the flat surface 21a, so that the force acting via the lever arms 12a and 12b upon the upper pressure plate 19 is thereby reduced. The provision of the angularly adjustable semi-cylindrical member 21, therefore, makes it possible to vary the ratio of pressure exerted upon the upper surface and the lateral surface of the coil portion in conformity with the cross-section of the latter. The second power component B is absorbed by the bearing 13, provided that this hearing is stationarily positioned in the block 1. If the pivot 13 is displaceably arranged in the rotatable supporting arms 14, as shown in the embodiments of Figs. 1 to 4, the power component B has to be absorbed by an abutment 27 provided at the block 1 and against which the supporting-arms 14 areenabled to bear.

As shown in the diagrammatic illustration of Fig. 5, every increase in the angle of rotation of the fiat surface 21a with respect to the surface 10a of the angle lever 10 results automatically in a decrease in value of the components C1, C2, C3 and in an increase in value of the components B1, B2, B3, which increase, however, is without ditficulty absorbed by the pivot 13 or the abutment 27.

What I claim as new and desire to'secure by Letters Patent of the United States is:

1. In a device for pressing insulating material around the long and straight-lined coil members of motors, generators and the like, a supporting body; an elongated angle member provided with means for its heating horizontally mounted on said supporting body and into which said coil member surrounded by the insulating material is placed; an elongated lateral pressure member of rectangular crosssection loosely arranged in said elongated angle member laterally of said coil member for pressing said coil member against the vertically extending flange of said angle member; an elongated upper pressure member of rectangular'cross-section loosely placed on the upper surface of said coil member for pressing said coil member against the horizontally extending flange of said angle member; two double-armed levers pivotally mounted and suitably positioned at said supporting body, one of said levers being adapted to exert with one of its arms compressivepressure against said upper press-member, and the other one of said levers being adapted to exert with one of its arms compressive pressure against said lateral pressure member; a working cylinder provided with a hydraulically actuated piston and piston-rod; and coupling means coupling said double-armed pressure exerting lever of said upper pressure member to said working cylinder and coupling said double-armed pressure exerting lever of said lateral pressure member to said piston-rod in such a way that actuation of said hydraulic piston results in simultaneous actuation via said coupling means of said two double-armed levers and their pressure exerting arms, said coupling means coupling said double-armed pressure exerting lever of said upper pressure member to said working cylinder consisting of an angle lever rotatably mounted at said supporting body and having one of its lever arms rigidly connected to said cylinder and the other one of its lever arms suitably devised and positioned for rotation of its appertaining double-armed lever, and said coupling means coupling said double-armed pressure exerting lever of said lateral pressure member to said piston-rod consisting of a pressure bolt shiftably arranged against spring resistance in a bore of said supporting body and having one of its ends rest against its appertaining double-armed lever and its other end against the free end of said piston-rod for actuation by the latter.

2. A pressing device as specified in claim 1, including a pair of supporting arms rotatably fastened at their lower end at said supporting body and pivotally supporting between their upper ends said double-armed pressure exerting lever of said upper pressuremember; stop means suitably devised and arranged to limit the rotation of said pair of supporting arms to a certain predetermined angle of rotation; connecting means connecting said pair of su porting arms with said angle lever'connect'ed to said cyl inder in such a way that rotation of said angle lever owing to displacement of said hydraulic piston primarily only results in rotation of said pair of supporting arms through the angle permitted by said stop means, while continued rotation of said angle lever thereupon only results in rotation of the appertaining double-armed lever about its pivot, whereby the construction is so devised that the double-armed pressure exerting lever of the upper pressure member has at the moment of its rotation its pressure exerting arm-end positioned directly above said upper pressure member.

3. A pressing device as specified in claim 1, including a pair of supporting arms rotatably fastened at their lower end at said supporting body and pivotally supporting between their upper ends said double-arrned pressure exerting lever of said upper pressure member; stop means suitably devised and arranged to limit the rotation of said pair of supporting armsto a certain predetermined angle of rotation; connecting means connecting said pair of supporting arms with said angle lever connected to said cylinder in such a way that rotation of said angle lever owing to displacement of said hydraulic piston primarily only results in rotation of said pair of supporting arms through the angle permitted by said stop means, while continued rotation of said angle lever thereupon only results in rotation of the appertaining double-armed lever about its pivot, whereby the construction is so devised that the double-armed pressure exerting lever of the upper pressure member has at the moment of its rotation its pressure exerting arm-end positioned directly above said upper pressure member, said connecting means consisting of spring means secured at one end to said angle lever and at their other end to said pair of supporting arms and devised and arranged in such a way that upon rotation of said pair of supporting arms through the angle permitted by said stop means and upon rotation of the double-armed lever supported by said pair of supporting arms into pressure exerting position said angle lever bears against said pair of supporting arms with said spring means in compressed condition.

4. A pressing device as specified in claim 1, including a pair of supporting arms rotatably fastened at their lower end at said supporting body and pivotally supporting between their upper ends said double-armed pressure exerting lever of said upper pressure member; stop means suitably devised and arranged to limit the rotation of said pair of supporting arms to a certain predetermined angle of rotation; connecting means connecting said pair of supporting arms with said angle lever connected to said cylinder in such a way that rotation of said angle lever owing to displacement of said hydraulic piston primarily only results in rotation of said pair of supporting arms through the angle permitted by said stop means, while continued rotation of said angle lever thereupon only results in rotation of the appertaining double-armed lever about its pivot, whereby the construction is so devised that the double-armed pressure exerting lever. of the upper pressure member has at the moment of its rotation its pressure exerting arm-end positioned directly above said upper pressure member, said connecting means consisting of a rod pivotally secured at one end to said angle lever, a compression spring mounted on said rod, and a ringshaped member secured to said supporting arms and through which the free end of said rod shiftably extends.

5. In a device for pressing insulating material around the long and straight-lined coil members of rotors, generators and the like, a supporting body; an elongated angle member provided with means for its heating horizontally mounted on said supporting body and into which said coil member surrounded by the insulating material is placed; an elongated lateral pressure member of rectangular cross-section loosely arranged in said elongated angle member laterally of said coil member for pressing said coil member against the vertically extending flange of said angle member; an elongated upper pressure member of rectangular cross-section loosely placed on the upper surface of said coil member for pressing said coil member against the horizontally extending flange of said angle member; two double-armed levers pivotally mounted and suitably positioned at said supporting body, one of said levers being adapted to exert with one of its arms compressive pressure against said upper pressure member, and the other one of said levers being adapted to exert withone of its arms compressive pressure against said lateral pressuremember; a working cylinder provided with a hydraulically actuated pistonandpiston-rod;

and coupling means coupling said double-armed pressure exerting lever of said upper pressure member to said and positioned to bear against its appertaining doublearmed lever for rotation of the latter, said angle lever being provided at the place of its surface at which it bears against one arm of its appertaining double-armed lever with a rotatable surface portion adapted for rotatory adjustment of its surface in angular position to the bearing surface of the angle lever, so that through rotation of said rotatable surface portion into said angular position the resultant of the pressure exerted by said angle lever upon one arm of its appertaining double-armed lever is resolved into two components of which one is effective in vertical direction of the surface of said rotatable surface portion and thus forms the pressure component for the rotation of the appertaining double-armed lever, while the other pressure component is absorbed by the bearing means of the appertaining lever.

6. A pressing device as specified in claim 5, including a roll rotatably mounted at the end of the arm of said double-armed lever against which said rotatable surface portion of the bearing surface of said angle lever bears for rotation of the lever; and in which said rotatable surface portion consists of a semi-cylindrical member rotatably mounted in a semi-cylindrical recess of said bearing surface of said angle lever and adapted for being locked in any desired angular position with respect to the bearing surface of said angle lever.

7. A pressing device as specified in claim 5, in which said rotatable surface portion consists of a semi-cylindrical member rotatably mounted in a semi-cylindrical recess of said bearing surface of said angle lever; and including locking means for locking said semi-cylindrical member in any desired angular position with respect to said bearing surface of said angle lever, said locking means consisting of a pair of flanges rigidly fastened to said semi-cylindrical member and embracing said angle lever in fork-like fashion and provided with a bore-hole, a plurality of bore-holes provided in said angle lever on the same are of a circle about the axis of rotation of said semi-cylindrical member as said bore-hole in said pair of fork-like flanges, and a bolt adapted for being pushed through said bore-hole in said fork-like flanges and through one of said bore-holes in said angle lever.

8. In a device for pressing insulating material around the long and straight-lined coil members of motors, generators and the like, a supporting body; an elongated angle member provided with means for its heating horizontally mounted on said supporting body and into which said coil member surrounded by the insulating material is placed; an elongated lateral pressure member of rectangular cross-section loosely arranged in said elongated angle member laterally of said coil member for pressing said coil member against the vertically extending flange of said angle member; an elongated upper pressure member of rectangular cross-section loosely placed on the upper surface of said coil member for pressing said coil member against the horizontally extending flange of said angle member; two double-armed levers pivotally mounted and suitably positioned at said supporting body, one of said levers being seated at the end of a pair of rotatably mounted supporting arms provided with stop means for their rotation and adapted *to exert with one of its arms 9 compressive pressure against said upper pressure member, and the other one of said levers being adapted to exert with one of its arms compressive pressure against said lateral pressure member; hydraulically actuated operating means; and coupling means coupling said double-- armed pressure exerting lever of said upper pressure member and said double-armed pressure exerting lever of said lateral pressure member to said hydraulic operating means in such manner that actuation of said hydraulic operating means results in simultaneous actuation via said coupling means of said two double-armed levers and their pressure exerting arms, said coupling means coupling said double-armed pressure exerting lever of said upper pressure member to said hydraulic operating means consisting of an angle lever rotatably mounted at said supporting body and having one of its lever arms rigidly connected to said hydraulic operating means and the other one of its lever arms suitably devised and positioned for rotation of its appertaining double-armed lever and of connecting means resiliently connecting said pair of supporting arms to said angle lever and urging said double-armed pressure exerting lever of the upper pres- 10 sure member in the direction toward said angle lever, said coupling means and said stop means being adapted for cooperation with said hydraulic operating means and with V the appertaining double-armed lever in such manner that actuation of said hydraulic operating means results first in rotation of said supporting arms through such an angle that the pressure exerting end of the appertaining double-armed lever is thereby moved into a position directly above said upper pressure member, whereupon continued actuation of said hydraulic operating means causes said pressure exerting end of the lever to bear against said upper pressure member.

References Cited in the file of this patent UNITED STATES PATENTS 1,823,923 Duerr Sept. 15, 1931 2,009,824 Walter July 30, 1935 2,072,694 Walter Mar. 2, 1937 FOREIGN PATENTS 1,041,122 France May 27, 1953 

